Windows installer MSI format

Question

I cannot find the MSI format specification. It says that its an open standard, but I don\'t see any documentation - just bits and pieces of information here and there.

Answer 1

The MSI file format is not open and is in fact undocumented, however the API required to access these files is part of the Windows Installer SDK. That link describes both the API functions required to access and modify MSI databases (files), and the contents of the tables in an MSI database.

That said if you want to modify or view the contents of an MSI then the easiest way to do it is probably just to use an editor that someone else has made (which will in turn use these functions). The ones that I know of are:

• ORCA
• InstEd
• InstallShield also have an MSI editor

If you really want to know more about the details of the internals of the MSI file format then take a read through of these two blog articles by Rob Mensching (the author of WiX)

• Inside the MSI file format
• Inside the MSI file format, again